A magnetic device including a magnetic element is described. The magnetic element includes a fixed layer having a fixed layer magnetization, a spacer layer that is nonmagnetic, and a free layer having a free layer magnetization. The free layer is changeable due to spin transfer when a write current above a threshold is passed through the first free layer. The free layer is includes low saturation magnetization materials.
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1. A device comprising: one or more magnetic memory cells, each one of the magnetic memory cells including: a magnetic element including: a first fixed layer having a fixed layer magnetization; a first spacer layer that is nonmagnetic; and a first free layer having a free layer magnetization that is changeable due to spin transfer when a write current above a threshold is passed through the first free layer; the first spacer layer residing between the first fixed layer and the first free layer, the first free layer including at least one ferromagnetic material and at least one nonmagnetic material, wherein the at least one nonmagnetic material is selected from a group consisting of W, Ti, V, and Hf to lower the threshold of the write current for the first free layer including the at least one nonmagnetic material compared to the first free layer not including the at least one nonmagnetic material; and a circuit comprising at least an isolation transistor electrically connected to the magnetic element to control the write current through the magnetic element.
A magnetic memory device contains magnetic memory cells. Each cell includes a magnetic element: a fixed magnetic layer with a set magnetization direction, a non-magnetic spacer layer, and a free magnetic layer. The free layer's magnetization can be flipped by passing a write current above a certain threshold. The spacer layer sits between the fixed and free layers. The free layer is made of both ferromagnetic (e.g., Cobalt, Iron, Nickel) and nonmagnetic materials (Tungsten, Titanium, Vanadium, or Hafnium) to reduce the write current threshold, making it easier to switch the free layer's magnetization compared to a free layer without these nonmagnetic materials. A circuit including an isolation transistor controls the write current through this magnetic element.
2. The device of claim 1 , wherein the ferromagnetic material of the first free layer includes at least one of Co, Ni, or Fe.
The magnetic memory device described previously (containing magnetic memory cells, each with a magnetic element of fixed and free layers separated by a non-magnetic spacer, with the free layer's magnetization changeable by a write current, the free layer including ferromagnetic and non-magnetic materials like Tungsten, Titanium, Vanadium, or Hafnium to reduce the write current threshold, and a circuit with isolation transistor controlling current) has a free layer where the ferromagnetic material is Cobalt, Nickel, or Iron.
3. The device of claim 1 , wherein the ferromagnetic material of the first free layer includes at least one of alloy of CoNi, CoFe, NiFe, or CoNiFe.
The magnetic memory device described previously (containing magnetic memory cells, each with a magnetic element of fixed and free layers separated by a non-magnetic spacer, with the free layer's magnetization changeable by a write current, the free layer including ferromagnetic and non-magnetic materials like Tungsten, Titanium, Vanadium, or Hafnium to reduce the write current threshold, and a circuit with isolation transistor controlling current) has a free layer where the ferromagnetic material is an alloy of CoNi, CoFe, NiFe, or CoNiFe.
4. The device of claim 1 , wherein the first free layer includes at least five atomic percent and less than or equal to fifty atomic percent W, Ti, V, or Hf.
The magnetic memory device described previously (containing magnetic memory cells, each with a magnetic element of fixed and free layers separated by a non-magnetic spacer, with the free layer's magnetization changeable by a write current, the free layer including ferromagnetic and non-magnetic materials like Tungsten, Titanium, Vanadium, or Hafnium to reduce the write current threshold, and a circuit with isolation transistor controlling current) has a free layer containing between 5 and 50 atomic percent of Tungsten, Titanium, Vanadium, or Hafnium.
5. The device of claim 1 , wherein the first spacer layer includes an insulating material.
The magnetic memory device described previously (containing magnetic memory cells, each with a magnetic element of fixed and free layers separated by a non-magnetic spacer, with the free layer's magnetization changeable by a write current, the free layer including ferromagnetic and non-magnetic materials like Tungsten, Titanium, Vanadium, or Hafnium to reduce the write current threshold, and a circuit with isolation transistor controlling current) uses an insulating material for the non-magnetic spacer layer.
6. The device of claim 5 , wherein the insulating material includes Al 2 O 3 or MgO.
The magnetic memory device described previously (containing magnetic memory cells, each with a magnetic element of fixed and free layers separated by a non-magnetic spacer, with the free layer's magnetization changeable by a write current, the free layer including ferromagnetic and non-magnetic materials like Tungsten, Titanium, Vanadium, or Hafnium to reduce the write current threshold, and a circuit with isolation transistor controlling current, using an insulating material for the non-magnetic spacer layer) uses Aluminum Oxide (Al2O3) or Magnesium Oxide (MgO) as the insulating material for the spacer layer.
7. The device of claim 1 , wherein the first spacer layer includes a conducting layer.
The magnetic memory device described previously (containing magnetic memory cells, each with a magnetic element of fixed and free layers separated by a non-magnetic spacer, with the free layer's magnetization changeable by a write current, the free layer including ferromagnetic and non-magnetic materials like Tungsten, Titanium, Vanadium, or Hafnium to reduce the write current threshold, and a circuit with isolation transistor controlling current) uses a conducting material for the non-magnetic spacer layer.
8. The device of claim 7 , wherein the conducting layer includes at least one of Ru, Re, Cu, Ta or Cu, and an alloy that includes Ru, Re, Cu, Ta or Cu.
The magnetic memory device described previously (containing magnetic memory cells, each with a magnetic element of fixed and free layers separated by a non-magnetic spacer, with the free layer's magnetization changeable by a write current, the free layer including ferromagnetic and non-magnetic materials like Tungsten, Titanium, Vanadium, or Hafnium to reduce the write current threshold, and a circuit with isolation transistor controlling current, using a conducting material for the non-magnetic spacer layer) uses Ruthenium (Ru), Rhenium (Re), Copper (Cu), or Tantalum (Ta), or an alloy of these materials for the conducting spacer layer.
9. The device of claim 1 , wherein the first fixed layer includes at least one ferromagnetic material and at least one nonmagnetic material, and the nonmagnetic material includes at least one of W, Ti, V, or Hf.
The magnetic memory device described previously (containing magnetic memory cells, each with a magnetic element of fixed and free layers separated by a non-magnetic spacer, with the free layer's magnetization changeable by a write current, the free layer including ferromagnetic and non-magnetic materials like Tungsten, Titanium, Vanadium, or Hafnium to reduce the write current threshold, and a circuit with isolation transistor controlling current) includes a fixed layer that also contains both ferromagnetic and nonmagnetic materials, with the nonmagnetic material being Tungsten, Titanium, Vanadium, or Hafnium.
10. The device of claim 1 , wherein the magnetic element further comprises: a second spacer layer that is nonmagnetic, the first free layer residing between the second spacer layer and the first spacer layer; and a second fixed layer, the second spacer layer residing between the second fixed layer and the first free layer.
The magnetic memory device described previously (containing magnetic memory cells, each with a magnetic element of fixed and free layers separated by a non-magnetic spacer, with the free layer's magnetization changeable by a write current, the free layer including ferromagnetic and non-magnetic materials like Tungsten, Titanium, Vanadium, or Hafnium to reduce the write current threshold, and a circuit with isolation transistor controlling current) now includes a second non-magnetic spacer layer and a second fixed magnetic layer. The first free layer resides between the first and second spacer layers, and the second spacer layer resides between the first free layer and the second fixed layer. This creates a structure: Fixed Layer 2 - Spacer Layer 2 - Free Layer 1 - Spacer Layer 1 - Fixed Layer 1.
11. The device of claim 10 , wherein the first spacer layer includes an insulating material and the second spacer layer includes an insulating material.
The magnetic memory device described previously (containing magnetic memory cells, each with a magnetic element of two fixed layers and one free layer, separated by two non-magnetic spacer layers, with the free layer's magnetization changeable by a write current, the free layer including ferromagnetic and non-magnetic materials like Tungsten, Titanium, Vanadium, or Hafnium to reduce the write current threshold, and a circuit with isolation transistor controlling current) uses insulating materials for BOTH the first and second spacer layers.
12. The device of claim 10 , wherein the first spacer layer includes a conducting material and the second spacer layer includes an insulating material.
The magnetic memory device described previously (containing magnetic memory cells, each with a magnetic element of two fixed layers and one free layer, separated by two non-magnetic spacer layers, with the free layer's magnetization changeable by a write current, the free layer including ferromagnetic and non-magnetic materials like Tungsten, Titanium, Vanadium, or Hafnium to reduce the write current threshold, and a circuit with isolation transistor controlling current) uses a conducting material for the first spacer layer and an insulating material for the second spacer layer.
13. The device of claim 1 , wherein the magnetic element further comprises: a first separation layer, the first free layer residing between the first spacer layer and the first separation layer; a second free layer having a free layer magnetization that is changeable due to a magnetic field created by the first free layer, the first separation layer residing between the first free layer and the second free layer; a second spacer layer that is nonmagnetic, the second free layer residing between the second spacer layer and the first separation layer; and a second fixed layer having a fixed layer magnetization, the second spacer layer residing between the second fixed layer and the second free layer.
The magnetic memory device described previously (containing magnetic memory cells, each with a magnetic element of fixed and free layers separated by a non-magnetic spacer, with the free layer's magnetization changeable by a write current, the free layer including ferromagnetic and non-magnetic materials like Tungsten, Titanium, Vanadium, or Hafnium to reduce the write current threshold, and a circuit with isolation transistor controlling current) includes a first separation layer, a second free layer, a second spacer layer, and a second fixed layer. The first free layer is between the first spacer layer and the first separation layer. The second free layer's magnetization is changed by a magnetic field created by the first free layer, and is separated from the first free layer by the first separation layer. The second spacer layer separates the second free layer and the second fixed layer. This creates a structure: Fixed Layer 2 - Spacer Layer 2 - Free Layer 2 - Separation Layer 1 - Free Layer 1 - Spacer Layer 1 - Fixed Layer 1.
14. The device of claim 1 , comprising a plurality of the magnetic memory cells.
The magnetic memory device, with magnetic memory cells each with a magnetic element of fixed and free layers separated by a non-magnetic spacer, with the free layer's magnetization changeable by a write current, the free layer including ferromagnetic and non-magnetic materials like Tungsten, Titanium, Vanadium, or Hafnium to reduce the write current threshold, and a circuit with isolation transistor controlling current, contains multiple of these magnetic memory cells.
15. The device of claim 1 , further comprising: a conductor line; and a plurality of the magnetic memory cells, each magnetic memory cell being electrically connected to the conductor line to receive the write current.
The magnetic memory device described previously (containing multiple magnetic memory cells, each with a magnetic element of fixed and free layers separated by a non-magnetic spacer, with the free layer's magnetization changeable by a write current, the free layer including ferromagnetic and non-magnetic materials like Tungsten, Titanium, Vanadium, or Hafnium to reduce the write current threshold, and a circuit with isolation transistor controlling current), further contains a conductor line where each magnetic memory cell is connected to the conductor line in order to receive the write current.
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June 14, 2011
July 2, 2013
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